A personal computer (PC) is provided with a chip (core chip) having a logic (state machine) for managing the power state thereof including operations of internal registers for storing the current power state of the PC. The state machine of the core chip is used to manage the power state of the PC including ON/OFF of the power supply. The interface (I/F) provided with the core chip state machine is standardized now. For a PC conforming to the ACPI (Advanced Configuration and Power Interface), an operating system (OS) is used to control the I/F provided with the state machine. The power supply of such the PC is turned off in response to a POWER OFF command issued to the power supply unit via the state machine after various termination processings related to the power off are executed by the OS.
Usually, therefore, such a power shut-off processing is executed in response to a power-on or power-off command issued from the OS or due to an ON/OFF operation of the power switch after a start-up including a power-on or termination processing; the power supply is not turned on nor turned off by the ON/OFF operation of the power switch.
By the way, a PC rectifies an AC power supplied from an AC power source and generates a DC voltage appropriate to itself from the rectified power (voltage) with use of various regulators. Concretely, the PC has various power sources used in itself. For example, the electric circuitry uses a plurality of such power sources as 5V, 3.3V, 12V, etc. These power sources are often provided as separated power sources to be turned on/off in an energy-saving mode for enabling those power sources to be turned off when the PC is in the off state and turned on as needed. Consequently, the PC executes such a power shut-off processing after a start-up processing including a power-on or termination processing for each of a plurality of such power sources as 5V, 3.3V, etc. in response to a power-on or power-off command issued from the OS and due to a power switch ON/OFF operation. Those power sources (5V, 3.3V, etc.) are used for the above described electronic circuitry. However, because a power supply unit used to obtain those DC powers from an AC power causes the size of the whole apparatus to be expanded, part of each power source, before its electric power is rectified once, is often provided as a power module.
And generally, a PC uses a voltage generated on the secondary winding when an AC voltage from an AC power source is rectified for full waves and the full-wave rectified voltage is supplied to the primary winding of a transformer so as to generate various DC voltages used for the PC itself. As known well, if a full-wave rectified voltage is supplied to the primary winding of a transformer so as to generate a voltage on the secondary winding, the efficiency is degraded. This is why the power factor is improved (refer to the official gazette of Published Unexamined Patent Application No. 9-9626). A circuitry used for this power factor correction (hereafter, to be referred to as a power factor correction circuitry) is provided between the input side of the AC power source and the above described transformer.
As described above, a PC executes a power shut-off processing after a start-up processing including a power-on or termination processing in response to a power-on or power-off command generated from the OS or due to an on/off operation of the power switch. However, a power source actuated by such a start-up processing and a power shut-off processing is used for various regulators that convert a voltage generated on the secondary winding of the transformer to a voltage usable by the PC respectively. Consequently, an electric power is kept supplied to the power factor correction circuitry.
This is why a voltage is kept generated on the secondary winding by supplying the full-wave rectified voltage to the primary winding of the transformer. Consequently, the electric power is kept consumed due to the operation of the power factor correction circuitry. And, this is why it has not been possible to reduce the power consumption in the power supply unit including the power factor correction circuitry even when the PC is in the off state.
Under such circumstances, it is an object of the present invention to provide an active filter used for a computer, which can reduce a power consumption under certain conditions such as power off and can conform to the regulated values of power line harmonics of various countries, as well as a filter module, a power module, and a computer.
The active filter of the present invention used for a computer includes a power factor correction circuitry and enabling means. The power factor correction circuitry supplies an electric power rectified from an AC input to the primary winding of a transformer intermittently so as to supply an electric power generated on the secondary winding of the transformer to the computer. Consequently, a voltage whose power factor is improved is generated on the secondary winding of the transformer. Concretely, the power factor as an electric power load observed from the AC power supply side is improved.
The computer of the present invention outputs a command signal so as to turn on/off a power source. The command signal directs supply of an electric power to the computer and it includes a signal for turning on/off an object power source. This command signal is entered via input means provided in enabling means. If the input means receives a command signal for supplying an electric power to the computer, the enabling means actuates the power factor correction circuitry. Consequently, the power factor correction circuitry is actuated only when receiving a command signal for directing supply of the electric power to the computer from the computer. It is thus possible to reduce the power consumption in the power factor correction circuitry, because the power factor correction circuitry is in the off state when no power supply is required for the computer.
The enabling means, when receiving a shut-off signal as the command signal for shutting off supply of an electric power to the computer, can stop the operation of the power factor correction circuitry. Concretely, when the command signal is a shut-off signal for directing shutting off of supply of an electric power to the computer, the enabling means becomes positive to stop the operation of the power factor correction circuitry, thereby reducing the power consumption in the power factor correction circuitry.
The present invention also provides a filter module formed so as to have the power factor correction circuitry and the enabling means in one and the same chip. Consequently, the present invention can improve the power factor with use of the chip and provide a filter module that can reduce the power consumption in the filter module.
The power module of the present invention includes a rectifier circuit for rectifying an AC input and this rectifier circuit outputs a rectified electric power. This rectified electric power is supplied to the primary winding of the transformer intermittently from the power factor correction circuitry, thereby the power factor is improved. The transformer is included in power supply means and this power supply means supplies an electric power generated on the secondary winding of the transformer to the computer. The power factor correction circuitry is actuated only when the input means receives an command signal for directing supply of an electric power to the computer. Consequently, the power factor correction circuitry is in the off state when no power supply to the computer is required. The power consumption in the power factor correction circuitry can thus be reduced. The present invention also provides a power module as a single unit, which can reduce the power consumption when the power supply to the computer is turned off.
In the power module, the enabling means can stop the operation of the power factor correction circuitry when receiving a shut-off signal as an command signal for shutting off supply of the electric power to the computer.
The power module can also be built in the computer or housed in an external case. As described above, therefore, the present invention can provide a computer that can reduce the power consumption when the electric power to the computer is turned off.
The computer of the present invention includes a rectifier circuit for rectifying an AC input and this rectifier circuit outputs a rectified electric power. This rectified electric power is supplied to the primary winding of the transformer intermittently from the power factor correction circuitry, thereby the power factor of the computer is improved. The above described transformer is included in power supply means and this power supply means supplies an electric power generated on the secondary winding of the transformer to the computer. The power supply means includes a constant use power source for keeping supply of an electric power generated on the secondary winding of the transformer to the computer and a selective power source for supplying an electric power to the computer when receiving an enabling signal for supplying the electric power to the computer. This constant use power source keeps supply of the minimum electric power to the computer. The power source is just requested to supply such the minimum necessary electric power so as to restore the power supply to the computer in such a mode as the energy-saving mode in response to a command from the OS. The power consumption in the mode is thus reduced to the minimum.
Consequently, a fixed voltage is kept supplied to the computer from the constant use power source. The fixed voltage is of an electric power generated on the secondary winding of the transformer. In addition, another fixed voltage is supplied to the computer from the selective power source only when the enabling signal is entered to the computer. The fixed voltage from the selective power source is of the electric power generated on the secondary winding of the transformer. The power factor correction circuitry is actuated only when the input means receives an command signal for directing supply of an electric power to the computer from the enabling means. When no power supply is directed, therefore, the power factor correction circuitry is set in the off state. Such an electric power is kept supplied only to the constant use power source, which requires no large electric power whose power factor must be improved. Only a minimum necessary electric power is thus supplied to the computer. When no power supply to the computer is directed, the power factor correction circuitry is in the off state and the power consumption in the circuitry can be reduced. The computer of the present invention can thus reduce the power consumption such way when the power of the computer is off.
The above described computer, when receiving a shut-off signal as an command signal for shutting off supply of an electric power to the computer, can stop the operation of the power factor correction circuitry.
The active filter for a computer, the filter module, the power module, and the computer of the present invention may also be composed so that an command signal output when an electric power supplied to the computer exceeds the first value is entered to the input means provided in the enabling means. This first value is predetermined according to the power consumption of the computer and it is a favorable electric power value required when the electric power supplied to the computer begins increasing, thereby the power factor should be improved.
The shut-off signal used as an command signal to be entered to the enabling means may be output when the electric power supplied to the computer is smaller than the second value. This second value is predetermined corresponding to the power consumption of the computer. The value is a favorable value denoting that the electric power supplied to the computer is reduced and thereby the power factor correction is not required. The second value may be the same as that first value or smaller than the first value.
A computer conforming to, for example, the ACPI Standard will be proper as the above described computer of the present invention.